mark_set_resources (insn, &insn_sets, 0, include_delayed_effects);
return resource_conflicts_p (&insn_sets, res);
}
-
-/* Return TRUE if INSN is a return, possibly with a filled delay slot. */
-
-static bool
-return_insn_p (rtx insn)
-{
- if (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) == RETURN)
- return true;
-
- if (GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) == SEQUENCE)
- return return_insn_p (XVECEXP (PATTERN (insn), 0, 0));
-
- return false;
-}
\f
-/* Find a label at the end of the function or before a RETURN. If there is
- none, make one. */
+/* Find a label at the end of the function or before a RETURN. If there
+ is none, try to make one. If that fails, returns 0.
+
+ The property of such a label is that it is placed just before the
+ epilogue or a bare RETURN insn, so that another bare RETURN can be
+ turned into a jump to the label unconditionally. In particular, the
+ label cannot be placed before a RETURN insn with a filled delay slot.
+
+ ??? There may be a problem with the current implementation. Suppose
+ we start with a bare RETURN insn and call find_end_label. It may set
+ end_of_function_label just before the RETURN. Suppose the machinery
+ is able to fill the delay slot of the RETURN insn afterwards. Then
+ end_of_function_label is no longer valid according to the property
+ described above and find_end_label will still return it unmodified.
+ Note that this is probably mitigated by the following observation:
+ once end_of_function_label is made, it is very likely the target of
+ a jump, so filling the delay slot of the RETURN will be much more
+ difficult. */
static rtx
find_end_label (void)
/* When a target threads its epilogue we might already have a
suitable return insn. If so put a label before it for the
end_of_function_label. */
- if (GET_CODE (insn) == BARRIER && return_insn_p (PREV_INSN (insn)))
+ if (GET_CODE (insn) == BARRIER
+ && GET_CODE (PREV_INSN (insn)) == JUMP_INSN
+ && GET_CODE (PATTERN (PREV_INSN (insn))) == RETURN)
{
rtx temp = PREV_INSN (PREV_INSN (insn));
end_of_function_label = gen_label_rtx ();
LABEL_NUSES (end_of_function_label) = 0;
- /* Put the label before an USE insn that may precede the RETURN insn. */
+ /* Put the label before an USE insns that may precede the RETURN insn. */
while (GET_CODE (temp) == USE)
temp = PREV_INSN (temp);
/* If the basic block reorder pass moves the return insn to
some other place try to locate it again and put our
end_of_function_label there. */
- while (insn && ! return_insn_p (insn))
+ while (insn && ! (GET_CODE (insn) == JUMP_INSN
+ && (GET_CODE (PATTERN (insn)) == RETURN)))
insn = PREV_INSN (insn);
if (insn)
{
}
else
{
+#ifdef HAVE_epilogue
+ if (HAVE_epilogue
+#ifdef HAVE_return
+ && ! HAVE_return
+#endif
+ )
+ {
+ /* The RETURN insn has its delay slot filled so we cannot
+ emit the label just before it. Since we already have
+ an epilogue and cannot emit a new RETURN, we cannot
+ emit the label at all. */
+ end_of_function_label = NULL_RTX;
+ return end_of_function_label;
+ }
+#endif /* HAVE_epilogue */
+
/* Otherwise, make a new label and emit a RETURN and BARRIER,
if needed. */
emit_label (end_of_function_label);
rtx trial = next_nonnote_insn (insn);
rtx next_trial = next_active_insn (trial);
rtx delay_list = 0;
- rtx target_label;
int flags;
flags = get_jump_flags (insn, JUMP_LABEL (insn));
&& (simplejump_p (next_trial)
|| GET_CODE (PATTERN (next_trial)) == RETURN))
{
- target_label = JUMP_LABEL (next_trial);
+ rtx target_label = JUMP_LABEL (next_trial);
if (target_label == 0)
target_label = find_end_label ();
- /* Recompute the flags based on TARGET_LABEL since threading
- the jump to TARGET_LABEL may change the direction of the
- jump (which may change the circumstances in which the
- delay slot is nullified). */
- flags = get_jump_flags (insn, target_label);
- if (eligible_for_annul_true (insn, 0, trial, flags))
- reorg_redirect_jump (insn, target_label);
+ if (target_label)
+ {
+ /* Recompute the flags based on TARGET_LABEL since threading
+ the jump to TARGET_LABEL may change the direction of the
+ jump (which may change the circumstances in which the
+ delay slot is nullified). */
+ flags = get_jump_flags (insn, target_label);
+ if (eligible_for_annul_true (insn, 0, trial, flags))
+ reorg_redirect_jump (insn, target_label);
+ }
}
INSN_ANNULLED_BRANCH_P (insn) = 1;
else
new_label = find_end_label ();
- delay_list
- = add_to_delay_list (copy_rtx (next_trial), delay_list);
- slots_filled++;
- reorg_redirect_jump (trial, new_label);
-
- /* If we merged because we both jumped to the same place,
- redirect the original insn also. */
- if (target)
- reorg_redirect_jump (insn, new_label);
+ if (new_label)
+ {
+ delay_list
+ = add_to_delay_list (copy_rtx (next_trial), delay_list);
+ slots_filled++;
+ reorg_redirect_jump (trial, new_label);
+
+ /* If we merged because we both jumped to the same place,
+ redirect the original insn also. */
+ if (target)
+ reorg_redirect_jump (insn, new_label);
+ }
}
}
else
label = get_label_before (new_thread);
- reorg_redirect_jump (insn, label);
+ if (label)
+ reorg_redirect_jump (insn, label);
}
return delay_list;
if (target_label == 0)
target_label = find_end_label ();
- if (next_active_insn (target_label) == next
+ if (target_label && next_active_insn (target_label) == next
&& ! condjump_in_parallel_p (insn))
{
delete_jump (insn);
continue;
}
- if (target_label != JUMP_LABEL (insn))
+ if (target_label && target_label != JUMP_LABEL (insn))
reorg_redirect_jump (insn, target_label);
/* See if this jump branches around an unconditional jump.
second jump. */
if (next && GET_CODE (next) == JUMP_INSN
&& (simplejump_p (next) || GET_CODE (PATTERN (next)) == RETURN)
+ && target_label
&& next_active_insn (target_label) == next_active_insn (next)
&& no_labels_between_p (insn, next))
{
if (trial == 0)
trial = find_end_label ();
- if (trial != target_label
+ if (trial && trial != target_label
&& redirect_with_delay_slots_safe_p (delay_insn, trial, insn))
{
reorg_redirect_jump (delay_insn, trial);
&& redundant_insn (trial, insn, 0)
&& ! can_throw_internal (trial))
{
- rtx tmp;
-
/* Figure out where to emit the special USE insn so we don't
later incorrectly compute register live/death info. */
- tmp = next_active_insn (trial);
+ rtx tmp = next_active_insn (trial);
if (tmp == 0)
tmp = find_end_label ();
- /* Insert the special USE insn and update dataflow info. */
- update_block (trial, tmp);
+ if (tmp)
+ {
+ /* Insert the special USE insn and update dataflow info. */
+ update_block (trial, tmp);
- /* Now emit a label before the special USE insn, and
- redirect our jump to the new label. */
- target_label = get_label_before (PREV_INSN (tmp));
- reorg_redirect_jump (delay_insn, target_label);
- next = insn;
- continue;
+ /* Now emit a label before the special USE insn, and
+ redirect our jump to the new label. */
+ target_label = get_label_before (PREV_INSN (tmp));
+ reorg_redirect_jump (delay_insn, target_label);
+ next = insn;
+ continue;
+ }
}
/* Similarly, if it is an unconditional jump with one insn in its
{
target_label = JUMP_LABEL (XVECEXP (PATTERN (trial), 0, 0));
if (target_label == 0)
- {
- target_label = find_end_label ();
- /* The following condition may be true if TRIAL contains
- the unique RETURN. In this case, threading would be
- a nop and we would enter an infinite loop if we did it. */
- if (next_active_insn (target_label) == trial)
- target_label = 0;
- }
+ target_label = find_end_label ();
if (target_label
- && redirect_with_delay_slots_safe_p (delay_insn, target_label,
+ && redirect_with_delay_slots_safe_p (delay_insn, target_label,
insn))
{
reorg_redirect_jump (delay_insn, target_label);
label = find_end_label ();
/* find_end_label can generate a new label. Check this first. */
- if (no_labels_between_p (insn, next)
+ if (label
+ && no_labels_between_p (insn, next)
&& redirect_with_delay_slots_safe_p (delay_insn, label, insn))
{
/* Be careful how we do this to avoid deleting code or labels
projects / gcc.git / commitdiff